What IP are you seeing (in ISPconfig) under Management > Settings > IP Address ?
And ISPmanagement > 'The-domain-that-you-created' > IP Address ?
Both should be the same, and they should be your LAN IP when you are behind a router.
re: If you want i can give you my ipaddress and the standard login data for my ISPConfig installation by pm? (so you can have a look at it).
Sorry. Normally I would help you with this, but at the moment I really do not have time.
Never execute code written on a Friday or a Monday.